Polyamide foams and process for their production

Abstract

A molding composition or mixture comprising a polyamide and at least one polymer containing sulfoxide groups serves for the production of a foam material by the action of heat. The foam material is used for moldings and heat-resistant insulation layers.

We claim: 
     
       1. A molding composition based on (A) at least one polyamide and (B) at least one polymer containing sulfoxide groups, and wherein the polymer containing sulfoxide groups is polyphenylene sulfoxide, polyphenylene sulfide sulfoxide or polyphenylene sulfide sulfoxide sulfone. 
     
     
       2. A molding composition based on (A) at least one polyamide and (B) at least one polymer containing sulfoxide groups, wherein the polymer containing sulfoxide groups comprises polyarylene sulfoxide units of the formula --(--C 6  H 4  --SO--)-- and wherein the arylene of the polymer containing sulfoxide groups is selected from the group consisting of monosubstituted monocyclic, polycyclic aromatic, a polysubstituted monocyclic and polycyclic aromatic. 
     
     
       3. A molding composition based on (A) at least one polyamide and (B) at least one polymer containing sulfoxide groups, and wherein the polyamide used is polyamide 46 or polyamide 66. 
     
     
       4. A molding composition as claimed in claim 1, containing from 1 to 99% by weight of the polymer containing sulfoxide groups. 
     
     
       5. A molding composition as claimed in claim 4, containing from 1 to 50% by weight of the polymer containing sulfoxide groups. 
     
     
       6. A molding composition as claimed in claim 5, containing from 3 to 20% by weight of the polymer containing sulfoxide groups. 
     
     
       7. A molding composition based on (A) at least one polyamide and (B) at least one polymer containing sulfoxide groups, obtained by heating the composition at a temperature at which any foam formation does not yet occur and at which the polyamide is present as a melt. 
     
     
       8. A molding composition as claimed in claim 1, wherein compound (B) has a sulfoxide content of at lest 50% (based on sulfur-containing bridges in the polymer). 
     
     
       9. A molding composition as claimed in claim 1, wherein component (B) has a sulfoxide content of at least 95% (based on all sulfur-containing bridges of the polymer. 
     
     
       10. A molding composition as claimed in claim 1, obtained by heating the composition at a temperature in the range from 200° C. to 450° C. for a time period of from 5 to 60 minutes to produce a foamed material.